Considerable effort has been directed toward the development of apparatus for increasing the safety of drivers and passengers when an automobile is involved in a head-on collision. For example, various passive restraint devices, such as lap shoulder belts, have been devised for use alone or together, or in combination with safety devices such as air bags and cushioned dashboard assemblies. While such safety equipment has increased vehicle safety dramatically, still submarining, the effect of the body sliding away from the seat, is a hazard, and many automobiles are not equipped with air bags because of the cost involved, and the use of seatbelts by both drivers and passengers is sporadic and often neglected.
In most instances involving a frontal crash of a motor vehicle there is a tendency for the vehicle to pivot upwardly about the front end of the vehicle. This action causes unweighting of the occupants so that their weight no longer presses their buttocks against the seat. In most crashes, therefore, the people riding in the automobile break away from the seats on which they are sitting and essentially are free to move forward while the vehicle rapidly decelerates. If passive belt restraints or airbags are employed, the upper body of the person will be stopped and become a pivot point for the body. Since a person's lower body has little or no contact and friction force with the seat, however, there is a tendency for the legs and lower body of the passenger to continue forward unrestrained and with the momentum which the person had immediately prior to the crash. The result can be submarining of a person's body out from under the passive restraints as the momentum of the mass of the lower body continues in the forward direction. This tendency is further aided by the natural reaction of a person to pull their slightly bent legs up toward their chest in a panic stop or crash. The result can be severe injury by reason of driving of the person's legs up into the dashboard assembly and/or steering column.
Studies of the dynamics of movement of a person's body during an automobile crash have often been based upon assumptions which in fact are not sound. The human body is, for example, quite flexible and does not act as a unit during rapid deceleration, particularly if only a portion of the body is restrained. It is highly desirable, therefore, to effect a controlled deceleration of substantially the entire mass of vehicle passenger, preferably at a rate which is not as high as the deceleration rate of a vehicle, during a crash.
In addition to issues of safety, any seating assembly is desirably designed so as to be comfortable to sit in under normal conditions for prolonged periods of time. A highly effective seat assembly for enhancing comfort during prolonged seating is the assembly disclosed in my U.S. Pat. No. 4,650,249 in which the seat is mounted for movement along an upwardly concaved arcuate path. Such a path allows the user to continuously balance his or her posture while seated on the chair. The seating system of U.S. Pat. No. 4,650,249 restores mobility and eliminates deformation of the lumbar spine while seated. It produces uniform pressure distribution across the buttocks and thighs and reduces muscular work to below the fatigue level by keeping the musculo-skeletal system relaxed, and yet dynamic. Such a movable seat counteracts the deadening effect of sitting and restores mobility to the seated user.
The pelvic tilt seat assembly of U.S. Pat. No. 4,650,249, however, is shown as incorporated into a seat assembly which has a torso support platform that is relatively stationary in its vertical position. Thus, when the seat moves along an arcuate path, the torso support will resist vertical torso displacements causes by movement of the seat, unless the user lifts the torso away from, or is not supporting the torso on, such a platform. The pelvic tilt seat of U.S. Pat. No. 4,650,249 is particularly effective, therefore, when incorporated into a stool-like seating assembly without a back or chest support, or when the user is using the seating assembly during the performance of tasks relative to a static environment and while not resting the front or back of his or her torso against a fixed support surface.
Accordingly, it is an object of the present invention to provide a seat assembly for motor vehicles, and for other applications, which has enhanced comfort and further, when employed in a motor vehicle, has enhanced safety.
It is another object of the present invention to provide a seat assembly for a vehicle which will increase the ability to control deceleration of the lower body and legs of a person seated on the seat assembly during a frontal collision.
Another object of the present invention is to provide a seat assembly which will enhance collision safety in conjunction with and even when passive restraint devices are not employed and air bags or the like have not been installed in the vehicle.
Still a further object of the present invention is to provide a seat assembly for a motor vehicle or the like which produces displacement of the legs of a person seated on the same in a manner greatly enhancing safety during a frontal collision of the vehicle.
It is a further object of the present invention to provide a seating assembly and method for support of a person during seating which provides greatly enhanced comfort and a more relaxed and yet dynamic support of the person's musculo-skeletal system during seating.
Still another object of the present invention is to provide an apparatus and method for vehicle seating of individuals which is relatively simple to construct and yet provides substantially enhanced comfort and safety.
Still a further object of the present invention is to provide a safety seating assembly for a vehicle or the like which can be retrofit to existing vehicle seat mounting structures.
It is also an object of the present invention to provide a seat assembly which is durable, reliable in its operation, relatively low in maintenance, and suitable for use in a wide range of environments.
The seat assembly and method of the present invention have other objects and features of advantage which will become apparent from, and are set forth in more detail in, the accompanying drawing and description of the Best Mode of Carrying Out the Invention.